Telomere length in leukocytes correlates with bone mineral density and is shorter in women with osteoporosis

Changing landscape of hematopoietic and mesenchymal cells and their interactions during aging and in age-related skeletal pathologies

Aging profoundly impacts mesenchymal and hematopoietic lineage cells, including their progenitors-the skeletal stem cells (SSCs) and hematopoietic stem cells (HSCs), respectively. SSCs are crucial for skeletal development, homeostasis, and regeneration, maintaining bone integrity by differentiating into osteoblasts, adipocytes, and other lineages that contribute to the bone marrow (BM) microenvironment. Meanwhile, HSCs sustain hematopoiesis and immune function. With aging, SSCs and HSCs undergo significant functional decline, partly driven by cellular senescence-a hallmark of aging characterized by irreversible growth arrest, secretion of pro-inflammatory factors (senescence associated secretory phenotype, SASP), and impaired regenerative potential. In SSCs, senescence skews lineage commitment toward adipogenesis at the expense of osteogenesis, contributing to increased bone marrow adiposity , reduced bone quality, and osteoporosis. Similarly, aged HSCs exhibit diminished self-renewal, biased differentiation, and heightened inflammation, compromising hematopoietic output and immune function. In this review, we examine the age-related cellular and molecular changes in SSCs and HSCs, their lineage decisions in the aging microenvironment, and the interplay between skeletal and hematopoietic compartments. We also discuss the role of senescence-driven alterations in BM homeostasis and how targeting cellular aging mechanisms may offer therapeutic strategies for mitigating age-related skeletal and hematopoietic decline.

The relationship between telomere length and aging-related diseases

The intensifying global phenomenon of an aging population has spurred a heightened emphasis on studies on aging and disorders associated with aging. Cellular senescence and aging are known to be caused by telomere shortening. Telomere length (TL) has emerged as a biomarker under intense scrutiny, and its widespread use in investigations of diseases tied to advancing age. This review summarizes the current knowledge of the association between telomeres and aging-related diseases, explores the important contribution of dysfunctional telomeres to the development and progression of these diseases, and aims to provide valuable insights for the development of novel therapeutic strategies.

Shorter Telomere Length Is Associated With Older Age, Poor Sleep Hygiene, and Orthopedic Injury, but Not Mild Traumatic Brain Injury, in a Cohort of Canadian Children

BACKGROUND

Predicting recovery following pediatric mild traumatic brain injury (mTBI) remains challenging. The identification of objective biomarkers for prognostic purposes could improve clinical outcomes. Telomere length (TL) has previously been used as a prognostic marker of cellular health in the context of mTBI and other neurobiological conditions. While psychosocial and environmental factors are associated with recovery outcomes following pediatric mTBI, the relationship between these factors and TL has not been investigated. This study sought to examine the relationships between TL and psychosocial and environmental factors, in a cohort of Canadian children with mTBI or orthopedic injury (OI).

METHODS

Saliva was collected at a postacute (median 7 days) timepoint following injury to assess TL from a prospective longitudinal cohort of children aged 8 to 17 years with either mTBI (n = 202) or OI (n = 90), recruited from 3 Canadian sites. Questionnaires regarding psychosocial and environmental factors were obtained at a postacute follow-up visit and injury outcomes were assessed at a 3-month visit. Univariable associations between TL and psychosocial, environmental, and outcome variables were assessed using Spearman's correlation. Further adjusted analyses of these associations were performed by including injury group, age, sex, and site as covariates in multivariable generalized linear models with a Poisson family, log link function, and robust variance estimates.

RESULTS

After adjusting for age, sex, and site, TL in participants with OI was 7% shorter than those with mTBI (adjusted mean ratio = 0.93; 95% confidence interval, 0.89-0.98; P = .003). As expected, increasing age was negatively associated with TL (Spearman's r = -0.14, P = .016). Sleep hygiene at 3 months was positively associated with TL (adjusted mean ratio = 1.010; 95% confidence interval, 1.001-1.020; P = .039).

CONCLUSION

The relationships between TL and psychosocial and environmental factors in pediatric mTBI and OI are complex. TL may provide information regarding sleep quality in children recovering from mTBI or OI; however, further investigation into TL biomarker validity should employ a noninjured comparison group.

High-throughput single telomere analysis using DNA microarray and fluorescent in situ hybridization

The human telomere system is highly dynamic. Both short and long leucocyte average telomere lengths (aTL) are associated with an increased risk of cancer and early death, illustrating the complex relationship between TL and human health and the importance of assessing TL distributions with single TL analysis. A DNA microarray and telomere fluorescent in situ hybridization (DNA-array-FISH) approach was developed to measure the base-pair (bp) lengths of single telomeres. On average 32000 telomeres were measured per DNA sample with one microarray chip assaying 96 test DNA samples. Various telomere parameters, i.e. aTL and the frequency of short/long telomeres, were computed to delineate TL distribution. The intra-assay and inter-assay coefficient of variations of aTL ranged from 1.37% to 3.98%. The correlation coefficient (r) of aTL in repeated measurements ranged from 0.91 to 1.00, demonstrating high measurement precision. aTLs measured by DNA-array-FISH predicted aTLs measured by terminal restriction fragment (TRF) analysis with r ranging 0.87-0.99. A new accurate and high-throughput method has been developed to measure the bp lengths of single telomeres. The large number of single TL data provides an opportunity for an in-depth analysis of telomere dynamics and the complex relationship between telomere and age-related diseases.

NRF2 signaling pathway and telomere length in aging and age-related diseases

The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is well recognized as a critical regulator of redox, metabolic, and protein homeostasis, as well as the regulation of inflammation. An age-associated decline in NRF2 activity may allow oxidative stress to remain unmitigated and affect key features associated with the aging phenotype, including telomere shortening. Telomeres, the protective caps of eukaryotic chromosomes, are highly susceptible to oxidative DNA damage, which can accelerate telomere shortening and, consequently, lead to premature senescence and genomic instability. In this review, we explore how the dysregulation of NRF2, coupled with an increase in oxidative stress, might be a major determinant of telomere shortening and age-related diseases. We discuss the relevance of the connection between NRF2 deficiency in aging and telomere attrition, emphasizing the importance of studying this functional link to enhance our understanding of aging pathologies. Finally, we present a number of compounds that possess the ability to restore NRF2 function, maintain a proper redox balance, and preserve telomere length during aging.

Senescence of skeletal stem cells and their contribution to age-related bone loss

Human aging is linked to bone loss, resulting in bone fragility and an increased risk of fractures. This is primarily due to an age-related decline in the function of bone-forming osteoblastic cells and accelerated cellular senescence within the bone microenvironment. Here, we provide a detailed discussion of the hypothesis that age-related defective bone formation is caused by senescence of skeletal stem cells, as they are the main source of bone forming osteoblastic cells and influence the composition of bone microenvironment. Furthermore, this review discusses potential strategies to target cellular senescence as an emerging approach to treat age-related bone loss.

Immune aging: biological mechanisms, clinical symptoms, and management in lung transplant recipients

While chronologic age can be precisely defined, clinical manifestations of advanced age occur in different ways and at different rates across individuals. The observed phenotype of advanced age likely reflects a superposition of several biological aging mechanisms which have gained increasing attention as the world contends with an aging population. Even within the immune system, there are multiple age-associated biological mechanisms at play, including telomere dysfunction, epigenetic dysregulation, immune senescence programs, and mitochondrial dysfunction. These biological mechanisms have associated clinical syndromes, such as telomere dysfunction leading to short telomere syndrome (STS), and optimal patient management may require recognition of biologically based aging syndromes. Within the clinical context of lung transplantation, select immune aging mechanisms are particularly pronounced. Indeed, STS is increasingly recognized as an indication for lung transplantation. At the same time, common aging phenotypes may be evoked by the stress of transplantation because lung allografts face a potent immune response, necessitating higher levels of immune suppression and associated toxicities, relative to other solid organs. Age-associated conditions exacerbated by lung transplant include bone marrow suppression, herpes viral infections, liver cirrhosis, hypogammaglobulinemia, frailty, and cancer risk. This review aims to dissect the molecular mechanisms of immune aging and describe their clinical manifestations in the context of lung transplantation. While these mechanisms are more likely to manifest in the context of lung transplantation, this mechanism-based approach to clinical syndromes of immune aging has broad relevance to geriatric medicine.

Exploring Causal Relationships between Leukocyte Telomere Length, Sex Hormone-Binding Globulin Levels, and Osteoporosis Using Univariable and Multivariable Mendelian Randomization

OBJECTIVE

Recent evidence supports that leukocyte telomere length (LTL) may be positively associated with healthy living and inversely correlated with the risk of age-related diseases, including osteoporosis. Furthermore, it is important to note that sex hormone-binding globulin (SHBG) levels play a crucial role in the regulation of osteoporosis by influencing the availability of sex hormones. Hence, this study holds significant importance as it aims to unravel the roles of LTL and SHBG levels and determine which one acts as a predominant intermediary factor in influencing osteoporosis. Using Mendelian randomization (MR), we can gain valuable insights into the intricate relationships between aging, sex hormones, and bone health.

METHODS

Univariable and multivariable and MR analyses were employed in this study. First, we used genetic variants associated with both LTL, as determined from a study involving 472,174 European participants by Codd et al., and SHBG levels, as identified in a study conducted by Ruth et al. with 370,125 participants, as instrumental variables (IVs). Then we aimed to establish a causal relationship between LTL and SHBG levels and their potential impact on osteoporosis using univariable MR. Finally, we conducted multivariable MR to provide insights into the independent and combined effects of LTL, SHBG levels on osteoporosis risk. We used various MR methods, with the primary analysis employing the inverse-variance weighted (IVW) model.

RESULTS

Univariable MR analysis reveals a potential causal effect of longer LTL on reduced risk of osteoporosis [odds ratio (OR): 0.85; 95% confidence interval (CI): 0.73-0.99; p = 0.03]. Conversely, higher genetically determined SHBG levels affect the risk of osteoporosis positively. (OR: 1.38; 95% CI: 1.09-1.75; p < 0.01). We observed a negative causal effect for LTL on the occurrence of SHBG (OR: 0.96; 95% CI 0.94-0.98, p < 0.01). After adjustment of using multivariable MR, the causal effect of LTL on osteoporosis (OR: 0.92; 95% CI: 0.84-1.03; p = 0.14), and the effect of SHBG on osteoporosis (OR: 1.43; 95% CI: 1.16-1.75; p < 0.01) were observed.

CONCLUSION

Longer LTL may confer a protective effect against osteoporosis. Additionally, the levels of SHBG appear to play a crucial role in mediating the relationship between LTL and osteoporosis. By understanding the interplay between these factors, we can gain valuable insights into the mechanisms underlying bone health and aging and potentially identify new avenues for prevention and intervention strategies.

Involvement of Inheritance in Determining Telomere Length beyond Environmental and Lifestyle Factors

All linear chromosomal ends have specific DNA-protein complexes called telomeres. Telomeres serve as a "molecular clock" to estimate the potential length of cell replication. Shortening of telomere length (TL) is associated with cellular senescence, aging, and various age-related diseases in humans. Here we reviewed the structure, function, and regulation of telomeres and the age-related diseases associated with telomere attrition. Among the various determinants of TL, we highlight the connection between TL and heredity to provide a new overview of genetic determinants for TL. Studies across multiple species have shown that maternal and paternal TL influence the TL of their offspring, and this may affect life span and their susceptibility to age-related diseases. Hence, we reviewed the linkage between TL and parental influences and the proposed mechanisms involved. More in-depth studies on the genetic mechanism for TL attrition are needed due to the potential application of this knowledge in human medicine to prevent premature frailty at its earliest stage, as well as promote health and longevity.

Telomere length as a predictive biomarker in osteoporosis (Review)

Telomeres are the ends of chromosomes that protect them from DNA damage. There is evidence to suggest that telomere shortening appears with advanced age. Since aging is a significant risk factor for developing age-related complications, it is plausible that telomere shortening may be involved in the development of osteoporosis. The present review summarizes the potential of telomere shortening as a biomarker for detecting the onset of osteoporosis. For the purposes of the present review, the following scientific databases were searched for relevant articles: PubMed/NCBI, Cochrane Library of Systematic Reviews, Scopus, Embase and Google Scholar. The present review includes randomized and non-randomized controlled studies and case series involving humans, irrespective of the time of their publication. In six out of the 11 included studies providing data on humans, there was at least a weak association between telomere length and osteoporosis, with the remaining studies exhibiting no such association. As a result, telomere shortening may be used as a biomarker or as part of a panel of biomarkers for tracking the onset and progression of osteoporosis.

Fructose intake and its association with relative telomere length: an exploratory study among healthy Lebanese adults

Introduction

Shorter relative telomere length (RTL) has been associated with increased incidence of morbidity. Although still disputed, available evidence suggests that dietary factors, including sugar-sweetened beverages (SSB) may be linked with shorter RTL. It was argued that the link between SSB and RTL may be explained by the sugar content of these beverages, and specifically fructose given its impact on oxidative stress and the inflammatory response. However, none of the existing studies have examined the specific link between fructose intake and RTL. This exploratory study aimed at (1) assessing the intake of dietary fructose (total, added and natural) in Lebanese healthy adults and (2) examining dietary fructose as a predictor of short telomere length.

Methods

Following a cross-sectional design (n = 282), anthropometric and biochemical data were collected. RTL was assessed by utilizing real-time polymerase chain reaction (RT-qPCR) to amplify both telomere and single-copy gene segments. Dietary intake was evaluated using a culture-specific food frequency questionnaire (FFQ). Intakes of added fructose, naturally-occurring fructose, and total fructose were estimated.

Results

Mean intakes of added and natural fructose were of 39.03 ± 34.12 and 12.28 ± 8.59 g/day, respectively, representing 4.80 ± 3.56 and 1.78 ± 1.41% of total energy intake (EI). Mean total fructose intake was of 51.31 ± 35.55 g/day, contributing 6.58 ± 3.71% EI. Higher intakes of total and added fructose were significantly associated with shorter RTL 2nd RTL tertile as compared to the 3rd RTL tertile; relative risk ratio (RRR) = 3.10 [95% confidence interval (CI): 1.38, 6.94] and RRR = 2.33 (95% CI: 1.02, 5.36), respectively after adjustment for confounders identified using a directed acyclic graph (DAG).

Conclusion

In conclusion, although we could not observe a dose-dependent relation between fructose intakes and RTL shortening and although the study is limited by its small sample size, the findings suggest that total and added dietary fructose intakes may be associated with shorter RTL. Larger studies, of longitudinal nature, are needed to further confirm the study findings.

Association of Telomere Length with Cognitive Impairment

Telomere attrition is attributed to Alzheimer's disease (AD), major depressive disorder, stress levels, physical inactivity, short sleep duration, and reduced educational abilities. In this article, we tried to assess the association between the telomere length in peripheral blood leukocytes and level of cognitive impairment and its dependence on age and sex. Healthy subjects and patients with amnestic mild cognitive impairment (aMCI) and different AD stages were recruited in the study. All patients were assessed by the same standard diagnostic procedure, including neurological examination-Mini-Mental State Examination (MMSE). Blood samples from 66 subjects (18 men and 48 women, mean age 71.2 ± 0.56 years) were collected for DNA extraction from peripheral mononuclear cells (PBMC). Relative telomere length (RTL) was measured by monochrome multiplex polymerase chain reaction. The data obtained in the study indicate that RTL in PBMCs has a statistically significant association with MMSE score (p < 0.02). Moreover, the sex-specific difference was observed for the association between telomere length and various parameters of MMSE. Also, it has been found that a decrease in RTL by one unit is associated with an increase in the odds to get AD at a ratio of 2.54 (95% CI, 1.25 to 5.17). The results obtained in this research are in coherence with other studies that telomere length may be a valuable biomarker of cognitive decline. However, the potential need for longitudinal studies of telomere length, in order to estimate the influence of hereditary and environmental factors, remains.

Functional association between telomeres, oxidation and mitochondria

Prior research has substantiated the vital role of telomeres in human fertility. Telomeres are prerequisites for maintaining the integrity of chromosomes by preventing the loss of genetic material following replication events. Little is known about the association between sperm telomere length and mitochondrial capacity involving its structure and functions. Mitochondria are structurally and functionally distinct organelles that are located on the spermatozoon's midpiece. Mitochondria produce adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS), which is necessary for sperm motility and generate reactive oxygen species (ROS). While a moderate concentration of ROS is critical for egg-sperm fusion, and fertilization, excessive ROS generation is primarily related to telomere shortening, sperm DNA fragmentation, and alterations in the methylation pattern leading to male infertility. This review aims to highlight the functional connection between mitochondria biogenesis and telomere length in male infertility, as mitochondrial lesions have a damaging impact on telomere length, leading both to telomere lengthening and reprogramming of mitochondrial biosynthesis. Furthermore, it aims to shed light on how both inositol and antioxidants can positively affect male fertility.

Lean body mass but not body fat mass is related with leukocyte telomere length in children

OBJECTIVES

The aim of this study was to investigate the relationship between body composition and leukocyte telomere length (LTL) in healthy Chinese children aged 6-11 years.

METHODS

This cross-sectional study enrolled 406 healthy children (175 girls and 231 boys). The relative telomere length in their peripheral blood leukocytes was determined via quantitative polymerase chain reaction. Dual-energy X-ray absorptiometry was used to determine body fat content and regional fat distribution, appendicular skeletal muscle mass (ASM), bone mineral density (BMD) and bone mineral content (BMC) at the total body (TB) and total body less head (TBLH) levels, and total body lean mass (TBLM) was then determined. ASM/height² (ASMI) was also calculated.

RESULTS

After adjusting for potential covariates, multiple linear regression analyses revealed that neither body fat content nor regional body fat distribution were significantly associated with LTL (β = -8.48 × 10^-6-1.44 × 10^-1, p = 0.227-0.959). However, ASM, ASMI, TB BMC/TB BMD, TBLH BMC/TBLH BMD and TBLM were positively associated with LTL (β = 8.95 × 10^-6-4.95 × 10^-1, p = 0.005-0.035). Moreover, analysis of covariance revealed there was a statistically significant dose-dependent positive association between LTL and ASM, TB BMC/BMD, TBLH BMC/BMD, and TBLM (p-trend = 0.002-0.025).

CONCLUSIONS

Skeletal muscle mass and bone mass but not body fat content or distribution were significantly associated with LTL in this pediatric population.

Relative Leukocyte Telomere Length and Genetic Variants in Telomere-Related Genes and Serum Levels Role in Age-Related Macular Degeneration

Telomere shortening is well known to be associated with ageing. Age is the most decisive risk factor for age-related macular degeneration (AMD) development. The older the individual, the higher the AMD risk. For this reason, we aimed to find any associations between telomere length, distribution of genetic variants in telomere-related genes (TERT, TERT-CLPTM1, TRF1, TRF2, and TNKS2), and serum TERF-1 and TERF2 levels on AMD development.

METHODS

Our study enrolled 342 patients with AMD and 177 healthy controls. Samples of DNA from peripheral blood leukocytes were extracted by DNA salting-out method. The genotyping of TERT rs2736098, rs401681 in TERT-CLPTM1 locus, TRF1 rs1545827, rs10107605, TNKS2 rs10509637, rs10509639, and TRF2 rs251796 and relative leukocyte telomere length (T/S) measurement were carried out using the real-time polymerase chain reaction method. Serum TERF-1 and TERF2 levels were measured by enzymatic immunoassay (ELISA).

RESULTS

We found longer telomeres in early AMD patients compared to the control group. Additionally, we revealed that minor allele C at TRF1 rs10107605 was associated with decreases the odds of both early and exudative AMD. Each minor allele G at TRF2 rs251796 and TRF1 rs1545827 C/T genotype and C/T+T/T genotypes, compared to the C/C genotype, increases the odds of having shorter telomeres. Furthermore, we found elevated TERF1 serum levels in the early AMD group compared to the control group.

CONCLUSIONS

In conclusion, these results suggest that relative leukocyte telomere length and genetic variants of TRF1 and TRF2 play a role in AMD development. Additionally, TERF1 is likely to be associated with early AMD.

Telomere Length and Risk of Incident Fracture and Arthroplasty: Findings From UK Biobank

We investigated independent associations between telomere length and risk of fracture and arthroplasty in UK Biobank participants. Leukocyte telomere length (LTL) was measured in baseline samples using a validated polymerase chain reaction (PCR) method. We used, in men and women separately, Cox proportional hazards models to calculate the hazard ratio (HR) for incident fracture (any, osteoporotic) or arthroplasty (hip or knee) over 1,186,410 person-years of follow-up. Covariates included age, white cell count, ethnicity, smoking, alcohol, physical activity, and menopause (women). In further analyses we adjusted for either estimated bone mineral density (eBMD) from heel quantitative ultrasound, handgrip strength, gait speed, total fat mass (bioimpedance), or blood biomarkers, all measured at baseline (2006-2010). We studied 59,500 women and 51,895 men, mean ± standard deviation (SD) age 56.4 ± 8.0 and 57.0 ± 8.3 years, respectively. During follow-up there were 5619 fractures; 5285 hip and 4261 knee arthroplasties. In confounder-adjusted models, longer LTL was associated with reduced risk of incident knee arthroplasty in both men (HR/SD 0.93; 95% confidence interval [CI], 0.88-0.97) and women (0.92; 95% CI, 0.88-0.96), and hip arthroplasty in men (0.91; 95% CI, 0.87-0.95), but not women (0.98; 95% CI, 0.94-1.01). Longer LTL was weakly associated with reduced risk of any incident fracture in women (HR/SD 0.96; 95% CI, 0.93-1.00) with less evidence in men (0.98; 95% CI, 0.93-1.02). Associations with incident outcomes were not materially altered by adjustment for heel eBMD, grip strength, gait speed, fat mass, or blood biomarker measures. In this, the largest study to date, longer LTL was associated with lower risk of incident knee or hip arthroplasty, but only weakly associated with lower risk of fracture. The relative risks were low at a population level, but our findings suggest that common factors acting on the myeloid and musculoskeletal systems might influence later life musculoskeletal outcomes. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Associations between leukocyte telomere length and osteosarcopenia in 20,400 adults aged 60 years and over: Data from the UK Biobank

PURPOSE

Two mechanisms implicated in telomere shortening are oxidative stress and inflammation, both of which are linked to bone and muscle loss suggesting a pathological link between telomere attrition and osteosarcopenia. Using older adults aged 60 years and over in the UK Biobank, we examined the association between leukocyte telomere length and osteosarcopenia.

METHODS

Baseline leukocyte telomere length was measured using a multiplex qPCR technique and expressed as the amount of the telomere amplification product (T) to that of a single-copy gene (S) (T/S ratio). Osteosarcopenia data was from the first imaging visit and defined by WHO criteria (femoral neck bone density T score ≤ -1) for osteopenia/osteoporosis plus either the EWGSOP2 (low appendicular lean mass/height2 and low grip strength) or SDOC (low grip strength and slow walking pace) criteria for sarcopenia. Binary or multinomial logistic regression models were used to associate telomere length and osteosarcopenia or its components, adjusting for the covariates: age, sex, race, education, Townsend deprivation index, alcohol, smoking, BMI/weight, physical activity levels.

RESULTS

Among 20,400 older adults (mean age: 67.79 ± 4.9 years, 53% men), the prevalence of osteosarcopenia by EWGSOP2 (n = 96, 0.47%) or SDOC (n = 205, 1%) criteria was low at the first imaging visit (mean 8.82 years after baseline). Baseline telomere length was not associated with osteosarcopenia by EWGSOP2 (Relative Risk (RR): 1.00, 95% CI: 0.82-1.23 comparing osteosarcopenia to normal (non-osteopenic, non-osteoporotic, and non-sarcopenic) per Standard Deviation (SD) increase in telomere length) or SDOC (RR: 0.95, 95% CI: 0.83-1.09) criteria. Longer telomere length was associated with a lower risk of slow walking pace (Odds Ratio: 0.92, 95% CI: 0.87-0.99 per SD increase in telomere length, p = 0.021). Telomere length, however, was not associated with low grip strength, low bone density or low appendicular lean mass/height2 (p > 0.05).

CONCLUSIONS

In this population-based study, telomere length was not associated with osteosarcopenia; however, slow walking pace was. Further studies are needed to reexamine this relationship, including a greater number of the oldest-old (≥75 years) where osteosarcopenia is more prevalent.

[The dual role of the menopausal hormonal therapy as the enhancer of pleiotropic telomere rejuvenation and the silencer of cellular aging (literature review)]

Present worldwide healthcare researches prove that female patients are more sensitive to the population aging. Menopause or climacteria (climax) - is not as ageing itself, but a physiological unstoppable process. The main task for a physician is to improve life quality for female despite of ageing problems. Menopausal hormone therapy (MHT) due to the estrogen component has an anti-inflammatory, antioxidant effect and promotes the expression of telomerase, which together changes the homeostasis and integrity of telomeres. The use of MHT for five years or more can not only significantly change the quality of life, but also increase its duration. Literature search was carried out in national (eLibrary, CyberLeninka.ru) and international (PubMed, Cochrane Library) databases in Russian and English. The priority was free access to the full text of articles. The choice of sources was prioritized for the period from 2019 to 2021. However, taking into account the insufficient knowledge of the chosen topic, the choice of sources dates back to 1989.

Telomere dysfunction in ageing and age-related diseases

Ageing organisms accumulate senescent cells that are thought to contribute to body dysfunction. Telomere shortening and damage are recognized causes of cellular senescence and ageing. Several human conditions associated with normal ageing are precipitated by accelerated telomere dysfunction. Here, we systematize a large body of evidence and propose a coherent perspective to recognize the broad contribution of telomeric dysfunction to human pathologies.

[Gerontological aspects of eye diseases]

The global rate of aging is rapidly rising due to the increase in life expectancy, and the number of age-related diseases - including eye diseases - is increasing. The most common eye conditions affecting people over 50 years old are age-related macular degeneration, cataract, glaucoma and diabetic retinopathy. Timely and effective treatment of age-related eye diseases requires a deeper understanding of the cellular mechanisms of aging.

Telomere length as a biomarker of aging and diseases

As research related to healthspan and lifespan has become a hot topic, the necessity for a reliable and practical biomarker of aging (BoA), which can provide information about mortality and morbidity risk, along with remaining life expectancy, has increased. The chromosome terminus non-coding protective structure that prevents genomic instability is called a telomere. The continual shortening of telomeres, which affects their structure as well as function, is a hallmark of agedness. The aforementioned process is a potential cause of age-related diseases (ARDs), leading to a bad prognosis and a low survival rate, which compromise health and longevity. Hence, studies scrutinizing the BoAs often include telomere length (TL) as a prospective candidate. The results of these studies suggest that TL measurement can only provide an approximate appraisal of the aging rate, and its implementation into clinical practice and routine use as a BoA has many limitations and challenges. Nevertheless, measuring TL while determining other biomarkers can be used to assess biological age. This review focuses on the importance of telomeres in health, senescence, and diseases, as well as on summarizing the results and conclusions of previous studies evaluating TL as a potential BoA.

Misexpression of genes lacking CpG islands drives degenerative changes during aging

Cellular aging is characterized by disruption of the nuclear lamina and its associated heterochromatin. How these structural changes within the nucleus contribute to age-related degeneration of the organism is unclear. Genes lacking CpG islands (CGI− genes) generally associate with heterochromatin when they are inactive. Here, we show that the expression of these genes is globally activated in aged cells and tissues. This CGI− gene misexpression is a common feature of normal and pathological aging in mice and humans. We report evidence that CGI− gene up-regulation is directly responsible for age-related physiological deterioration, notably for increased secretion of inflammatory mediators.

Telomeres and Cancer

Telomeres cap the ends of eukaryotic chromosomes and are indispensable chromatin structures for genome protection and replication. Telomere length maintenance has been attributed to several functional modulators, including telomerase, the shelterin complex, and the CST complex, synergizing with DNA replication, repair, and the RNA metabolism pathway components. As dysfunctional telomere maintenance and telomerase activation are associated with several human diseases, including cancer, the molecular mechanisms behind telomere length regulation and protection need particular emphasis. Cancer cells exhibit telomerase activation, enabling replicative immortality. Telomerase reverse transcriptase (TERT) activation is involved in cancer development through diverse activities other than mediating telomere elongation. This review describes the telomere functions, the role of functional modulators, the implications in cancer development, and the future therapeutic opportunities.

Telomeres and Age-Related Diseases

Telomeres are at the non-coding ends of linear chromosomes. Through a complex 3-dimensional structure, they protect the coding DNA and ensure appropriate separation of chromosomes. Aging is characterized by a progressive shortening of telomeres, which compromises their structure and function. Because of their protective function for genomic DNA, telomeres appear to play an important role in the development and progression of many age-related diseases, such as cardiovascular disease (CVD), malignancies, dementia, and osteoporosis. Despite substantial evidence that links telomere length with these conditions, the nature of these observations remains insufficiently understood. Therefore, future studies should address the question of causality. Furthermore, analytical methods should be further improved with the aim to provide informative and comparable results. This review summarize the actual knowledge of telomere biology and the possible implications of telomere dysfunction for the development and progression of age-related diseases. Furthermore, we provide an overview of analytical techniques for the measurement of telomere length and telomerase activity.

Regular, Intense Exercise Training as a Healthy Aging Lifestyle Strategy: Preventing DNA Damage, Telomere Shortening and Adverse DNA Methylation Changes Over a Lifetime

Exercise training is one of the few therapeutic interventions that improves health span by delaying the onset of age-related diseases and preventing early death. The length of telomeres, the 5'-TTAGGG n -3' tandem repeats at the ends of mammalian chromosomes, is one of the main indicators of biological age. Telomeres undergo shortening with each cellular division. This subsequently leads to alterations in the expression of several genes that encode vital proteins with critical functions in many tissues throughout the body, and ultimately impacts cardiovascular, immune and muscle physiology. The sub-telomeric DNA is comprised of heavily methylated, heterochromatin. Methylation and histone acetylation are two of the most well-studied examples of the epigenetic modifications that occur on histone proteins. DNA methylation is the type of epigenetic modification that alters gene expression without modifying gene sequence. Although diet, genetic predisposition and a healthy lifestyle seem to alter DNA methylation and telomere length (TL), recent evidence suggests that training status or physical fitness are some of the major factors that control DNA structural modifications. In fact, TL is positively associated with cardiorespiratory fitness, physical activity level (sedentary, active, moderately trained, or elite) and training intensity, but is shorter in over-trained athletes. Similarly, somatic cells are vulnerable to exercise-induced epigenetic modification, including DNA methylation. Exercise-training load, however, depends on intensity and volume (duration and frequency). Training load-dependent responses in genomic profiles could underpin the discordant physiological and physical responses to exercise. In the current review, we will discuss the role of various forms of exercise training in the regulation of DNA damage, TL and DNA methylation status in humans, to provide an update on the influence exercise training has on biological aging.

A Comprehensive, Multidisciplinary, Personalized, Lifestyle Intervention Program Is Associated with Increased Leukocyte Telomere Length in Children and Adolescents with Overweight and Obesity

Leucocyte telomere length (LTL) is a robust marker of biological aging and is associated with obesity and cardiometabolic risk factors in childhood and adolescence. We investigated the effect of a structured, comprehensive, multidisciplinary, personalized, lifestyle intervention program of healthy diet and physical exercise on LTL in 508 children and adolescents (239 males, 269 females; 282 prepubertal, 226 pubertal), aged 10.14 ± 0.13 years. Participants were classified as obese (n = 267, 52.6%), overweight (n = 174, 34.2%), or of normal BMI (n = 67, 13.2%) according to the International Obesity Task Force (IOTF) cutoff points and were studied prospectively for one year. We demonstrated that LTL increased significantly after 1 year of the lifestyle interventions, irrespective of gender, pubertal status, or body mass index (BMI). Waist circumference was the best negative predictor of LTL at initial assessment. The implementation of the lifestyle interventions also resulted in a significant improvement in clinical (BMI, BMI z-score and waist to height ratio) and body composition indices of obesity, inflammatory markers, hepatic enzymes, glycated hemoglobin (HbA1C), quantitative insulin sensitivity check index (QUICKI), and lipid profile in all participants. These findings indicate that the increased LTL may be associated with a more favorable metabolic profile and decreased morbidity later in life.

Telomere dynamics across the early life course: Findings from a longitudinal study in children

Telomeres are protective caps on chromosome ends that shorten with each cell division. Telomere length (TL) predicts the onset of cellular senescence and correlates with longevity and age-related disease risk. Previous research suggests that adults display fixed ranking and tracking of TL by age 20 years, supporting the importance of TL at birth and attrition during childhood. However, longitudinal research examining telomere dynamics during early life is sparse. Here, we used monochrome multiplex quantitative polymerase chain reaction to measure relative TL in leukocytes isolated from cord blood and child blood collected at ages 3, 5, 7, and 9 years among 224 minority children enrolled in a New York City-based birth cohort. We also measured maternal TL at delivery in a subset of 197 participants with a biobanked blood sample. TL decreased most rapidly in the first years of life (birth to 3 years), followed by a period of maintenance into the pre-puberty period. Mothers with longer telomeres gave birth to newborns with longer telomeres that remained longer across childhood, suggesting that the fixed ranking and tracking of TL observed among adults may extend to early childhood or even the prenatal period with a potential transgenerational basis. We did not find significant sex differences in the pattern of child TL change across development. These findings emphasize the need to understand factors and mechanisms that determine TL during early childhood.

Function of telomere in aging and age related diseases

Telomeres consist of specialized non-coding DNA repeat sequences. They are essential for preserving the integrity of the genome during cancer development, senescence. Mammalian telomeres might have 1-50 kb of telomeric DNA, which becomes 40-200 base pairs shorter after per cell cycle, and becomes 5-8 kilobase shorter during senescence. There are many studies on the correlation of telomere length and aging rate. However, as the differences in the methods used in the studies and the scarcity of prospective studies, factors affecting telomere length are not really well understood. Some of the age related diseases may develop due to telomere dysfunction and telomere shortness. The short telomere structure detected in both peripheral blood leukocytes and cells of the disease-related tissue has the feature of being a predictive marker for many age-related diseases. It is expected that with future research, telomere length analysis is expected to enter clinical practice.

Bone Aging, Cellular Senescence, and Osteoporosis

Changes in aging bone that lead to osteoporosis are mediated at multiple levels, including hormonal alterations, skeletal unloading, and accumulation of senescent cells. This pathological interplay is superimposed upon medical conditions, potentially bone-wasting medications, modifiable and unmodifiable personal risk factors, and genetic predisposition that accelerate bone loss with aging. In this study, the focus is on bone hemostasis and its dysregulation with aging. The major physiological changes with aging in bone and the role of cellular senescence in contributing to age-related osteoporosis are summarized. The aspects of bone aging are reviewed including remodeling deficits, uncoupling phenomena, inducers of cellular senescence related to bone aging, roles of the senescence-associated secretory phenotype, radiation-induced bone loss as a model for bone aging, and the accumulation of senescent cells in the bone microenvironment as a predominant mechanism for age-related osteoporosis. The study also addresses the rationale and potential for therapeutic interventions based on the clearance of senescent cells or suppression of the senescence-associated secretory phenotype. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Telomere Length and Oxidative Stress and Its Relation with Metabolic Syndrome Components in the Aging

A great amount of scientific evidence supports that Oxidative Stress (OxS) can contribute to telomeric attrition and also plays an important role in the development of certain age-related diseases, among them the metabolic syndrome (MetS), which is characterised by clinical and biochemical alterations such as obesity, dyslipidaemia, arterial hypertension, hyperglycaemia, and insulin resistance, all of which are considered as risk factors for type 2 diabetes mellitus (T2DM) and cardiovascular diseases, which are associated in turn with an increase of OxS. In this sense, we review scientific evidence that supports the association between OxS with telomere length (TL) dynamics and the relationship with MetS components in aging. It was analysed whether each MetS component affects the telomere length separately or if they all affect it together. Likewise, this review provides a summary of the structure and function of telomeres and telomerase, the mechanisms of telomeric DNA repair, how telomere length may influence the fate of cells or be linked to inflammation and the development of age-related diseases, and finally, how the lifestyles can affect telomere length.

TERRA Gene Expression in Gastric Cancer: Role of hTERT

PURPOSE

One of the most important serious malignancies is gastric cancer (GC) with a high mortality globally. In this way, beside the environmental factors, genetic parameter has a remarkable effective fluctuation in GC. Correspondingly, telomeres are nucleoprotein structures measuring the length of telomeres and they have special potential in diagnosis of various types of cancers. Defect protection of the telomeric length initiates the instability of the genome during cancer, including gastric cancer. The most common way of maintaining telomere length is the function of the telomerase enzyme that replicates the TTAGGG to the end of the 3' chromosome.

METHODS

In this review, we want to discuss the alterations of hTERT repression on the modification of TERRA gene expression in conjunction with the importance of telomere and telomerase in GC.

RESULTS

The telomerase enzyme contains two essential components called telomerase reverse transcriptase (hTERT) and RNA telomerase (hTR, hTERC). Deregulation of hTERT plays a key role in the multistage process of tumorigenicity and anticancer drug resistance. The direct relationship between telomerase activity and hTERT has led to hTERT to be considered a key target for cancer treatment. Recent results show that telomeres are transcribed into telomeric repeat-containing RNA (TERRA) in mammalian cells and are long noncoding RNAs (lncRNAs) identified in different tissues. In addition, most chemotherapy methods have a lot of side effects on normal cells.

CONCLUSION

Telomere and telomerase are useful therapeutic goal. According to the main roles of hTERT in tumorigenesis, growth, migration, and cancer invasion, hTERT and regulatory mechanisms that control the expression of hTERT are attractive therapeutic targets for cancer treatment.

Polygenic basis and biomedical consequences of telomere length variation

Telomeres, the end fragments of chromosomes, play key roles in cellular proliferation and senescence. Here we characterize the genetic architecture of naturally occurring variation in leukocyte telomere length (LTL) and identify causal links between LTL and biomedical phenotypes in 472,174 well-characterized UK Biobank participants. We identified 197 independent sentinel variants associated with LTL at 138 genomic loci (108 new). Genetically determined differences in LTL were associated with multiple biological traits, ranging from height to bone marrow function, as well as several diseases spanning neoplastic, vascular and inflammatory pathologies. Finally, we estimated that, at the age of 40 years, people with an LTL >1 s.d. shorter than the population mean had a 2.5-year-lower life expectancy compared with the group with ≥1 s.d. longer LDL. Overall, we furnish new insights into the genetic regulation of LTL, reveal wide-ranging influences of LTL on physiological traits, diseases and longevity, and provide a powerful resource available to the global research community.

Mendelian randomization study of telomere length and bone mineral density

Purpose: Some epidemiological studies and animal studies have reported a relationship between leukocyte telomere length (LTL) and bone mineral density (BMD). However, the causality underlying the purported relationship has not been determined. Here we performed a two-sample MR analysis to test the causal link between telomere length and BMD.

Results: Our research suggested no causal link of LTL and BMD using IVW method. The weighted median, MR-Egger regression and MR.RAPS method yielded a similar pattern of effects. MR-Egger intercept test demonstrated our results were not influenced by pleiotropy. Heterogeneities among the genetic variants on heel estimated BMD and TB-BMD vanished after excluding rs6028466. “Leave-one-out” sensitivity analysis confirmed the stability of our results.

Conclusion: Our MR analysis did not support causal effect of telomere length on BMD.

Methods: We utilized 5 independent SNPs robustly associated with LTL as instrument variables. The outcome results were obtained from GWAS summary data of BMD. The two-sample MR analysis was conducted using IVW, weighted median, MR-Egger regression and MR.RAPS method. MR-Egger intercept test, Cochran’s Q test and I² statistics and “leave-one-out” sensitivity analysis were performed to evaluate the horizontal pleiotropy, heterogeneities and stability of these genetic variants on BMD.

The Association Between Leukocyte Telomere Length and Cognitive Performance Among the American Elderly

Background

Age-related cognitive decline begins in middle age and persists with age. Leukocyte telomere length (LTL) decreases with age and is enhanced by inflammation and oxidative stress. However, whether shorter LTL correlates with cognitive decline remains controversial.

Aims

We aimed to investigate the relationship between LTL and cognitive decline in the American elderly.

Methods

We used data from the 1999 to 2002 U.S. National Health and Nutrition Examination Survey (NHANES). We included participants aged 65–80 with available data on LTL and cognitive assessments. The cognitive function assessment used the digit symbol substitution test (DSST). We applied multivariate modeling to estimate the association between LTL and cognitive performance. Additionally, to ensure robust data analysis, we converted LTL into categorical variables through quartile and then calculated the P for trend.

Results

After adjusting for age, cardiovascular disease (CAD) score, gender, race, body mass index (BMI), and educational level, LTL showed a positive correlation with DSST score (odds ratio [OR] 3.47 [0.14, 6.79], P = 0.04). Additionally, to further quantify the LTL–DSST interaction, we found a similar trend when LTL was regarded as a categorical variable (quartile) (P for trend = 0.03).

Conclusion

LTL was associated with cognitive capabilities among the elderly, implying that LTL might be a biomarker of cognitive aging.

Can telomere length predict bone health? A review of current evidence

Telomeres are repetitive DNA sequences located at the end of chromosomes that serve as a protective barrier against chromosomal deterioration during cell division. Approximately 50–200 base pairs of nucleotides are lost per cell division, and new repetitive nucleotides are added by the enzyme telomerase, allowing telomere maintenance. Telomere shortening has been proposed as an indicator for biological aging, but its relationship with age-related osteoporosis is ambiguous. We summarize the current evidence on the relationship between telomere length and bone health in experimental and epidemiological studies, which serve as a scientific reference for the development of novel diagnostic markers of osteoporosis or novel therapeutics targeting telomere and telomerase of bone cells to treat osteoporosis.

Effect of plasma polyunsaturated fatty acid levels on leukocyte telomere lengths in the Singaporean Chinese population

BACKGROUND

Shorter telomere length (TL) has been associated with poor health behaviors, increased risks of chronic diseases and early mortality. Excessive shortening of telomere is a marker of accelerated aging and can be influenced by oxidative stress and nutritional deficiency. Plasma n6:n3 polyunsaturated fatty acid (PUFA) ratio may impact cell aging. Increased dietary intake of marine n-3 PUFA is associated with reduced telomere attrition. However, the effect of plasma PUFA on leukocyte telomere length (LTL) and its interaction with genetic variants are not well established.

METHODS

A nested coronary artery disease (CAD) case-control study comprising 711 cases and 638 controls was conducted within the Singapore Chinese Health Study (SCHS). Samples genotyped with the Illumina ZhongHua-8 array. Plasma n-3 and n-6 PUFA were quantified using mass spectrometry (MS). LTL was measured with quantitative PCR method. Linear regression was used to test the association between PUFA and LTL. The interaction between plasma PUFAs and genetic variants was assessed by introducing an additional term (PUFA×genetic variant) in the regression model. Analysis was carried out in cases and controls separately and subsequently meta-analyzed using the inverse-variance weighted method. We further assessed the association of PUFA and LTL with CAD risk by Cox Proportional-Hazards model and whether the effect of PUFA on CAD was mediated through LTL by using structural equation modeling.

RESULTS

Higher n6:n3 ratio was significantly associated with shorter LTL (p = 0.018) and increased CAD risk (p = 0.005). These associations were mainly driven by elevated plasma total n-3 PUFAs, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (p < 0.05). There was a statistically significant interaction for an intergenic single nucleotide polymorphism (SNP) rs529143 with plasma total n-3 PUFA and DHA on LTL beyond the genome-wide threshold (p < 5 ×  10- 8). Mediation analysis showed that PUFA and LTL affected CAD risk independently.

CONCLUSIONS

Higher plasma n6:n3 PUFA ratio, and lower EPA and DHA n-3 PUFAs were associated with shorter LTL and increased CAD risk in this Chinese population. Furthermore, genetic variants may modify the effect of PUFAs on LTL. PUFA and LTL had independent effect on CAD risk in our study population.

Telomerase activation in the treatment of aging or degenerative diseases: a systematic review

Telomeres are protective structures that are shortened during the lifetime, resulting in aging and degenerative diseases. Subjects experiencing aging and degenerative disorders present smaller telomeres than young and healthy ones. The size of these structures can be stabilized by telomerase, an enzyme which is inactive in adult tissues but functional in fetal and newborn tissues and adult testes and ovaries. The aim of this study was to perform a systematic review to evaluate the effect of telomerase activation in the treatment of degenerative and aging disorders. We accomplished the search using the Pubmed interface for papers published from September 1985 to April 16th, 2020. We found twenty one studies that matched our eligibility criteria. I concluded that telomerase is probably a potential and safe treatment for aging and degenerative diseases, demonstrating neither side effects nor risk of cancer in the selected studies. Further studies in humans are needed to confirm safety and efficiency of this treatment.

Molecular Basis of Bone Aging

A decline in bone mass leading to an increased fracture risk is a common feature of age-related bone changes. The mechanisms underlying bone senescence are very complex and implicate systemic and local factors and are the result of the combination of several changes occurring at the cellular, tissue and structural levels; they include alterations of bone cell differentiation and activity, oxidative stress, genetic damage and the altered responses of bone cells to various biological signals and to mechanical loading. The molecular mechanisms responsible for these changes remain greatly unclear and many data derived from in vitro or animal studies appear to be conflicting and heterogeneous, probably due to the different experimental approaches; nevertheless, understanding the main physio-pathological processes that cause bone senescence is essential for the development of new potential therapeutic options for treating age-related bone loss. This article reviews the current knowledge concerning the molecular mechanisms underlying the pathogenesis of age-related bone changes.

Finding of novel telomeric repeats and their distribution in the human genome

Telomeres, the nucleoprotein structures, located at the end of the chromosomes are correlated with cancer and aging. The accelerated telomere attrition can accelerate human aging and leads to the progression of several cancers. Our work describes the finding of two novel telomeric repeats "CACAGA" and "TCTCTGCGCCTGCGCCGGCGCGGCGCGCC" and demonstrates their distribution in human chromosomes compare to the reported telomeric repeat TTAGGG. Simultaneously, the distance between the adjacent telomeric repeats (loop) was determined and the presence of shorter loops in the telomeric regions might address the correlation between the telomere attrition and senescence condition in human.

The relationship between mean telomere length and blood pressure: results from the National Health and Nutrition Examination Surveys

Background

Recent studies have shown that telomere length has significantly relationship with different age-related diseases. However, the relationship between mean telomere length (MTL) and elevated blood pressure (BP) has been unclear. Therefore, the aim of the recent study was tried to explore the association of MLT with BP.

Methods

There were 5,981 subjects from the National Health and Nutrition Examination Surveys (NHANES, 1999–2002) was included in analysis. The MTL was measured using the quantitative polymerase chain reaction (PCR) method and expressed in telomere-to-single copy gene (T/S) ratio and grouped into quartiles. Multivariate linear [expressed in beta and 95% confidence interval (CI)], logistic regression [odds ratios (ORs) and 95% CI] analyses and smooth curve fitting were performed to evaluate the relationship between MTL, BPs and the likelihood of hypertension.

Results

The mean age of the participants was 45.2±17.3 years, including 2,923 (48.9%) males. After adjusting for potential confounders, MLT was significantly related to the prevalence of hypertension (OR: 0.12, 95% CI: 0.02, 0.94; P=0.04). Smooth curve fitting found a non-linear relationship between MTL, the levels of systolic and diastolic blood pressure (SBP/DBP) and the prevalence of hypertension. The inflection points for the smooth curve of MLT were at 0.86, 1.02 and 0.80 (T/S ratio) respectively. The betas (95% CIs) for SBP [–12.58 (–20.07, –5.09), P<0.01 and 2.25 (0.07, 4.43), P=0.04] and DBP [4.88 (1.29, 8.47), P<0.01 and –3.30 (–5.54, –1.06), P<0.01], and ORs (95% CIs) for the prevalence of hypertension [0.02 (0.001, 9.71), P=0.15 and 0.26 (0.026, 2.60), P=0.25] on the left and right of the inflection point, respectively.

Conclusions

Our findings revealed that MTL was related with SBP, DBP and the odds of hypertension in a non-linear manner.

Organophosphate insecticide exposure and telomere length in U.S. adults

BACKGROUND

Organophosphate insecticides have been widely used for >30 years, and are reported to be associated with various age-related chronic diseases. While shortening of telomere length has been considered as a marker of cellular aging, only a few small studies have been conducted to examine any difference of telomere length in workers exposed to organophosphates versus controls. Epidemiologic studies of the dose-response associations between environmental organophosphate exposure and telomere length in the general population are few.

OBJECTIVE

This study aimed to evaluate the association between levels of organophosphate insecticide exposure and telomere length in the general population.

METHODS

We analyzed data for 1724 participants aged 20 years or more from the National Health and Nutrition Examination Survey 1999-2002. Organophosphate insecticide exposure was estimated using measures of urinary concentrations for 3,5,6-trichloro-2-pyridinol (TCPY) and six non-specific dialkyl phosphate metabolites, e.g., diethyl thiophosphate (DETP). Multiple linear regression was conducted to assess the association between organophosphate exposure and telomere length.

RESULTS

After controlling for sociodemographic and physical factors and urinary creatinine, participants in the second quartile for urinary TCPY had 0.06 (95% CI: 0.02-0.10) T/S ratio shorter telomere length than those in the lowest quartile. By contrast, participants in the second and third tertiles of urinary DETP had 0.08 (95% CI: 0.02-0.14) and 0.06 (95% CI, 0.01-0.11) T/S ratio longer telomere length than those in the lowest tertile. For other five metabolites, there was no association with telomere length.

CONCLUSIONS

Levels of environmental exposures to certain organophosphate insecticides may be linked to altered telomere length in adults in the general population. Although our findings may need to be replicated, we provide the first evidence that environmental exposure to organophosphates may contribute to the alteration of telomere length, which is potentially related to biological aging and to the development of various chronic diseases.

Respiratory

Lung disease rivals the position for the top cause of death worldwide. Causes and pathology of the myriad lung diseases are varied, yet nutrition can either affect the outcome or support treatment in the majority of cases. This chapter explores the modifiable risk factors, from lifestyle changes to dietary intake to specific nutrients, anti-nutrients, and toxins helpful for the nutritionist or dietitian working with lung disease patients. General lung health is discussed, and three major disease states are explored in detail, including alpha-1 antitrypsin deficiency, asthma, and idiopathic pulmonary fibrosis. Although all lung diseases have diverse causes, many integrative and functional medical nutrition therapies are available and are not being utilized in practice today. This chapter begins the path toward better nutrition education for the integrative and functional medicine professional.

Telomere length and telomerase activity in osteoporosis and osteoarthritis

Osteoarthritis (OA) and osteoporosis (OP) are associated skeletal pathologies and have as a distinct feature the abnormal reconstruction of the subchondral bone. OA and OP have been characterized as age-related diseases and have been associated with telomere shortening and altered telomerase activity (TA). This review discusses the role of telomeres and telomerase in OA and OP pathologies and focuses on the usability of telomere length (TL) and the rate of telomere shortening as potential disease biomarkers. A number of studies have demonstrated that telomere shortening may contribute to OA and OP as an epigenetic factor. Therefore, it has been claimed that the measurement of TL of chondrocytes and/or peripheral blood cells may be an appropriate marker for the evaluation of the progression of these diseases. However, there is a need to be perform further studies with larger cohorts, with the aim of obtaining objective results and a better understanding of the association between TL, inflammation and aging, in order to provide further insight into the pathophysiology of degenerative joint diseases.

The age modification to leukocyte telomere length effect on bone mineral density and osteoporosis among Chinese elderly women

Critically short telomeres indicate cellular senescence. Leukocyte telomere length (LTL) is regarded as an aging predictor. Osteoporosis is an age-related disease. The purpose of our study is to examine the association between LTL, and BMD and osteoporosis among an elderly Chinese population. A total of 1017 participants (584 postmenopausal women) with a mean age of 66.4 years were recruited from April 2016 to August 2017. Dual-energy X-ray absorptiometry was used for BMD measurement at skeleton sites of lumbar spine (LS), femoral neck (FN), and total hip (TH). LTL was measured using quantitative real-time polymerase chain reaction. Among women, age significantly modified the effect of LTL on BMD at FN. Additionally, significant age modification was observed for the association between LTL and LS BMD category (indicative of control or osteopenia or osteoporosis), and the number of osteoporotic sites at LS or TH. The corresponding estimates (95% CI) for the relative excess risk due to interaction (RERI) were - 0.07 (- 0.11, - 0.01) and - 0.11 (- 0.16, - 0.03) sequentially in ordinal logistic regression models. The estimated RERIs (95% CI) were - 0.11 (- 0.25, - 0.02) and - 0.23 (- 0.39, - 0.10) in multinomial logistic regression models for LS/FN/TH BMD category, and - 0.20 (- 0.31, - 0.09) and - 0.34 (- 0.49, - 0.21) for FN BMD category. However, similar findings did not show in men. The effect of LTL on BMD and osteoporosis risk is modified by age in elderly women but not in men, suggesting that the predictive role of LTL in bone loss differs by sex.

Telomere biology and age-related diseases

Telomeres are the protective end caps of chromosomes and shorten with every cell division. Telomere length has been proposed as a biomarker of biological age and a risk factor for age-related diseases. Epidemiologic studies show an association between leukocyte telomere length (LTL) and mortality. There is solid evidence that links LTL with cardiovascular disease. Short telomeres promote atherosclerosis and impair the repair of vascular lesions. Alzheimer's disease patients have also a reduced LTL. Telomeres measured in tumor tissue from breast, colon and prostate are shorter than in healthy tissue from the same organ and the same patient. In healthy tissue directly adjacent to these tumors, telomeres are also shorter than in cells that are more distant from the cancerous lesion. A reduced telomere length in cancer tissue from breast, colon and prostate is associated with an advanced disease state at diagnosis, faster disease progression and poorer survival. By contrast, results regarding LTL and cancer are inconsistent. Furthermore, the majority of studies did not find significant associations between LTL, bone mineral density (BMD) and osteoporosis. The present manuscript gives an overview about our current understanding of telomere biology and reviews existing knowledge regarding the relationship between telomere length and age-related diseases.

Telomeres in neurological disorders

Ever since their discovery, the telomeres and the telomerase have been topics of intensive research, first as a mechanism of cellular aging and later as an indicator of health and diseases in humans. By protecting the chromosome ends, the telomeres play a vital role in preserving the information in our genome. Telomeres shorten with age and the rate of telomere erosion provides insight into the proliferation history of cells. The pace of telomere attrition is known to increase at the onset of several pathological conditions. Telomere shortening has been emerging as a potential contributor in the pathogenesis of several neurological disorders including autism spectrum disorders (ASD), schizophrenia, Alzheimer's disease (AD), Parkinson's disease (PD) and depression. The rate of telomere attrition in the brain is slower than that of other tissues owing to the low rate of cell proliferation in brain. Telomere maintenance is crucial for the functioning of stem cells in brain. Taking together the studies on telomere attrition in various neurological disorders, an association between telomere shortening and disease status has been demonstrated in schizophrenia, AD and depression, in spite of a few negative reports. But, studies in ASD and PD have failed to produce conclusive results. The cause-effect relationship between TL and neurological disorders is yet to be elucidated. The factors responsible for telomere erosion, which have also been implicated in the pathogenesis of neurological disorders, need to be explored in detail. Telomerase activation is now being considered as a potential therapeutic strategy for neurological disorders.

Targeting Telomerase and ATRX/DAXX Inducing Tumor Senescence and Apoptosis in the Malignant Glioma

Glioblastoma multiforme (GBM) is a type of brain tumor that is notorious for its aggressiveness and invasiveness, and the complete removal of GBM is still not possible, even with advanced diagnostic strategies and extensive therapeutic plans. Its dismal prognosis and short survival time after diagnosis make it a crucial public health issue. Understanding the molecular mechanisms underlying GBM may inspire novel and effective treatments against this type of cancer. At a molecular level, almost all tumor cells exhibit telomerase activity (TA), which is a major means by which they achieve immortalization. Further studies show that promoter mutations are associated with increased TA and stable telomere length. Moreover, some tumors and immortalized cells maintain their telomeres with a telomerase-independent mechanism termed the “alternative lengthening of telomeres” (ALT), which relates to the mutations of the α-thalassemia/mental retardation syndrome X-linked protein (ATRX), the death-domain associated protein (DAXX) and H3.3. By means of the mutations of the telomerase reverse transcriptase (TERT) promoter and ATRX/DAXX, cancers can immortalize and escape cell senescence and apoptosis. In this article, we review the evidence for triggering GBM cell death by targeting telomerase and the ALT pathway, with an extra focus on a plant-derived compound, butylidene phthalide (BP), which may be a promising novel anticancer compound with good potential for clinical applications.

Body mass index is negatively associated with telomere length: a collaborative cross-sectional meta-analysis of 87 observational studies

Background

Even before the onset of age-related diseases, obesity might be a contributing factor to the cumulative burden of oxidative stress and chronic inflammation throughout the life course. Obesity may therefore contribute to accelerated shortening of telomeres. Consequently, obese persons are more likely to have shorter telomeres, but the association between body mass index (BMI) and leukocyte telomere length (TL) might differ across the life span and between ethnicities and sexes.

Objective

A collaborative cross-sectional meta-analysis of observational studies was conducted to investigate the associations between BMI and TL across the life span.

Design

Eighty-seven distinct study samples were included in the meta-analysis capturing data from 146,114 individuals. Study-specific age- and sex-adjusted regression coefficients were combined by using a random-effects model in which absolute [base pairs (bp)] and relative telomere to single-copy gene ratio (T/S ratio) TLs were regressed against BMI. Stratified analysis was performed by 3 age categories ("young": 18-60 y; "middle": 61-75 y; and "old": >75 y), sex, and ethnicity.

Results

Each unit increase in BMI corresponded to a -3.99 bp (95% CI: -5.17, -2.81 bp) difference in TL in the total pooled sample; among young adults, each unit increase in BMI corresponded to a -7.67 bp (95% CI: -10.03, -5.31 bp) difference. Each unit increase in BMI corresponded to a -1.58 × 10(-3) unit T/S ratio (0.16% decrease; 95% CI: -2.14 × 10(-3), -1.01 × 10(-3)) difference in age- and sex-adjusted relative TL in the total pooled sample; among young adults, each unit increase in BMI corresponded to a -2.58 × 10(-3) unit T/S ratio (0.26% decrease; 95% CI: -3.92 × 10(-3), -1.25 × 10(-3)). The associations were predominantly for the white pooled population. No sex differences were observed.

Conclusions

A higher BMI is associated with shorter telomeres, especially in younger individuals. The presently observed difference is not negligible. Meta-analyses of longitudinal studies evaluating change in body weight alongside change in TL are warranted.

Relationship of Absolute Telomere Length With Quality of Life, Exacerbations, and Mortality in COPD

BACKGROUND

COPD is an age-related disease. The role of cellular senescence in COPD has not been fully elucidated. This study examined the relationship between telomere length of peripheral blood leukocytes and clinical outcomes, including health status, rate of exacerbations, and risk of mortality in individuals with COPD.

METHODS

Using quantitative polymerase chain reaction, we measured the absolute telomere length (aTL) of DNA extracted from blood samples of 576 participants with moderate-to-severe COPD treated with either azithromycin or placebo for 12 months in the Macrolide Azithromycin for Prevention of Exacerbations of COPD (MACRO) study. All participants were followed for approximately 13 months, during which time health status and exacerbations were carefully ascertained, and an additional 29 months for mortality. The rates of exacerbation and mortality were determined by dividing the aTL into two groups using the median value as the cutoff.

RESULTS

Participants with shorter telomere length had worse health status defined by higher St. George's Respiratory Questionnaire scores (β = -0.09, P = .034). In the placebo arm of the study, the rate of exacerbation (rate ratio, 1.50; 95% CI, 1.16-1.95; P = .002) and the risk of mortality (hazard ratio, 9.45; 95% CI, 2.85-31.36; P = .015) were significantly higher in the shorter telomere group than in the longer telomere group; these differences were not observed in the azithromycin arm (interaction P = .008 for exacerbation and interaction P = .017 for mortality) CONCLUSIONS: These data suggest that replicative senescence may help to predict poor outcomes in COPD. Shorter leukocyte telomere lengths may represent a clinically translatable biomarker for identifying individuals at increased risk of poor clinical outcomes in COPD.

Premature Spinal Bone Loss in Women Living with HIV is Associated with Shorter Leukocyte Telomere Length

With advances in combination antiretroviral therapy (cART), people living with HIV are now surviving to experience aging. Evidence suggests that individuals living with HIV are at greater risk for low bone mineral density (BMD), osteoporosis, and fractures. Better understanding of the pathophysiology of bone health in women living with HIV (WLWH) is important for treatment strategies. The goal of this study was to explore new biological factors linked to low BMD in WLWH. Standardized BMD measures of WLWH were compared to reference values from an unselected population of women from the same geographical region of the same age range. Linear regression analysis was used to assess relationships among health-related characteristics, cellular aging (measured by leukocyte telomere length; LTL), cART, and BMD of WLWH. WLWH (n = 73; mean age 43 ± 9 years) had lower BMD Z-scores at the lumbar spine (LS) (mean difference = -0.39, p < 0.001) and total hip (TH) (-0.29, p = 0.012) relative to controls (n = 290). WLWH between 50 and 60 years (n = 17) had lower Z-scores at the LS (p = 0.008) and TH (p = 0.027) compared to controls (n = 167). Among WLWH, LS BMD was significantly associated with LTL (R² = 0.09, p = 0.009) and BMI (R² = 0.06, p = 0.042). Spinal BMD was adversely affected in WLWH. Reduction of LTL was strongly associated with lower BMD and may relate to its pathophysiology and premature aging in WLWH.